Ultrasonic imaging in the medical field is widely used for a variety of applications. In addition to imaging physiological structures and tissue such as organs, tumors, vessels, and the like, it is often desirable for a physician or technician to have an image of a medical device which has been inserted into the tissue or passageway of a patient. The types of devices which are surgically sterilized and inserted into patients are many. Typical examples include: needles, catheters and a variety of other medical products such as stents, dilators, pacing leads, introducers, angiography devices, angioplasty devices, pacemakers, in-patient appliances such as pumps and other devices. Various approaches have been used to enhance ultrasonic imaging by modifying the reflective surface characteristics of these devices.
U.S. Pat. No. 5,081,997 to Bosley, Jr. et al, for “Echogenic Devices, Material and Method” discloses a device such as a needle that includes an interface having a shape that is formed with a dimension that is less than a wavelength of the incident sonic beam. According to Bosley, Jr. et al., the shape includes a dimension such as a radius of curvature which is much less than the wavelength of the sonic beam. The interface may include the outside surface a device or article or material. That surface has a plurality of partially spherical indentations for producing a scattered component of the image in response to the incident beam. This image is produced regardless of the incident beam angle of which conventional devices depend for producing a reflected or constructive interference image. The scattered component of the image is produced when the radius of the partially spherical indentations or a dimension of another geometric shape or surface are much less than the wavelength of the incoming sonic beam.
Conventional recesses or dimples frequently have faces, bottoms and sides that are generally flat. For example, FIGS. 1-4 are photomicrographs illustrating a portion of an echogenic region from an EchoTip® needle available from Cook Medical, Bloomington, Indiana. As can be seen in these photomicrographs, the echogenic region contains recesses or dimples having generally flat bottoms and sides that are generally perpendicular to the needle surface and to the recess or dimple bottom. The recess or dimple bottom has a small groove which is believed to be an artifact of machining.
U.S. Patent Application Publication No. 2004/0249288 A1 to Ichikawa for “Ultrasonic Puncture Needle” discloses a device including an array of doughnut shaped recesses having a center portion remaining as a protrusion. According to US Publication No. 2004/0249288 A1, the recesses are also formed with faces, bottoms and sides being generally flat so to obtain reflection echoes with a great intensity for the incident ultrasonic waves with a shallow incident angle.
While the approaches described in U.S. Pat. No. 5,081,997 and U.S. Publication No. 2004/0249288 A1 have shown promise, improvements have been sought that would result in an interface that provides enhanced ultrasonic imaging, in a manner that is inexpensive to manufacture, and simple and reliable to use.